The design of a cost-effective, low-frequency, high power, high efficiency, omnidirectional acoustic projector remains a challenge due to conflicting constraints. For a given cavitation pressure threshold, high power requires a large radiation area while omni-directionality typically requires a projector with a dimension smaller than the third of a wavelength. Accordingly, there is a need for an acoustic projector design that addresses these conflicting requirements.
To achieve omni-directionality, current acoustic projectors (particularly for maritime uses) employ a large, heavy, towed projector, such as a free flooded ring (FFR). Due to the low resonant frequency of operation, despite being approximately up to a meter in diameter, the FFR appears as a point source and produces a substantially omni-directional wave. To achieve longer range, the acoustic projector needs to be driven with a high power signal, but the size and weight of the projector and the localized power intensity (because of the danger of cavitation at the face of the diaphragm) impose limits on the ability to increase the power of the drive signal.
Similar reference numerals may have been used in different figures to denote similar components.